EP1543088A1

EP1543088A1 - Novel adhesives comprising diacetals

Info

Publication number: EP1543088A1
Application number: EP03773781A
Authority: EP
Inventors: Antonio Pizzi; Philippe Faucher; Michela Zanetti
Original assignee: Clariant France SA
Current assignee: Clariant Speciality Fine Chemicals France
Priority date: 2002-09-25
Filing date: 2003-09-15
Publication date: 2005-06-22
Anticipated expiration: 2023-09-15
Also published as: DE60317354D1; FR2844802A1; AU2003282162A1; FR2844802B1; JP2006500471A; CN1685026A; US20060194918A1; TW200417590A; PL376046A1; TWI256968B; AR041371A1; ATE377639T1; NO20051012L; BR0314636A; EP1543088B1; WO2004029170A1; CA2499619A1

Abstract

A glue with high-mechanical resistance, comprising a diacetal which is linear or cyclic, which can be prepared from C2 -C6 aldehydes and C1 - C12 alcohols from agricultural waste, compositions of wood, papers or stratified cardboard containing said resin or glue or prepared using said glue and products prepared with the aid of said paper or stratified cardboard, and a method for glueing mineral fibres wherein the fibres are glued with the aid of a resin or the above-mentioned glue.

Description

New adhesives containing diacetals

The present invention relates to new adhesives containing diacetals and their uses.

We are always looking for better adhesives, providing good mechanical resistance to sticking.

EP-A-1 174 480 describes aminoplast or phenoplast adhesives containing an acetal of C ₁ -C ₆ alcohol and their use in the manufacture of wood particle boards. Examples are given of two monoacetals, namely methylal and ethylal.

FR-A-1 576 716 describes phenoplast adhesives containing an alcohol acetal in C-i-Cs used in particular for the manufacture of woody materials.

In the related field of papers and in particular laminated paper products (decorative laminate, sheet of decorative paper), numerous resins are used, for example melamine-formaldehyde, phenol-formaldehyde resins, as described in WO-A-97 / 00172, or WO-A-01/45940. EP-A-1 225 278 describes a method for impregnating decorative paper using a melamine resin, and papers thus produced.

Phenolic resins are also well known for their use in the preparation of binders for products based on mineral fibers, as described in EP-A-406498. Now, the Applicant has just discovered that the use of certain acetals, preferably diacetals, and in particular 1, 1, 2,2-tetramethoxyethane (hereinafter TME) gave resins and glues quite exceptional resistance, while being easier to handle industrially, due to its boiling and flash point temperatures. This is why the present invention relates to an adhesive characterized in that it contains a diacetal, linear or cyclic, which can be prepared from C ₂ -C ₈ dialdehydes and C ₁ -C ₁₂ alcohols. In the present application and in what follows, the term "adhesive" designates the compounds usually called "adhesives" or "resins".

By "diacetal" is meant the compounds which can be prepared from dialdehydes and alcohols, but also compositions which can make structures of the diacetal, monoacetal and hemiacetal type coexist.

Also by "diacetal" is meant the compounds which can be prepared from dialdehydes and polyols such as glycerol or pentaerythrol which lead to acetal compounds but also to compositions which can make structures of the diacetal, monoacetal and hemiacetal.

Under preferential conditions for implementing the invention, the adhesive contains a diacetal, and more particularly 1, 1, 2,2-tetramethoxyethane.

The diacetal used in the present invention can be prepared from aldehydes, C ₂ - C ₆ alcohols and Ci - Cι _2, preferably from C ₂ aldehydes - C ₄ alcohols and Cl - Cs, and more particularly from C ₂ - C ₃ aldehydes and Ci - C ₃ alcohols.

As examples, the diacetals can be 1, 1, 2,2-tetramethoxyethane (TME), 1, 1,2,2-tetraethoxyethane (TEE), 1, 1, 2,2, - tetrapropoxyethane ( TPE), 1, 1,3,3-tetramethoxypropane (TMP), 1, 1, 3,3-tetfaethoxypropane (TEP) and preferably TME.

One can also use in an adhesive according to the invention any combination of the acetals mentioned above, for example 2 or 3 acetals, or even 4 or more. The aldehydes from which the acetals which can be used according to the present invention can be prepared are, for example, dialdehydes such as glyoxal, malonaldehyde, glutaraldehyde.

The alcohols from which the acetals which can be used according to the present invention can be prepared are, for example, monoalcohols such as methanol, ethanol, diols such as ethylene glycol, diethylene glycol, 1,4-butanediol, neopentyl glycol or polyols such as glycerol or penta-erythrol. For example, it is considered that a diacetal such as TME can be prepared from glyoxal and methanol.

The adhesive may for example be an aminoplast adhesive, such as of the urea-resorcinol-formaldehyde, melamine-urea-phenol-formaldehyde, urea-formaldehyde type, preferably melamine-formaldehyde and particularly of the melamine-urea-formaldehyde type.

It can also be a phenoplast adhesive such as a phenol-urea-formaldehyde adhesive and preferably resorcinol-phenol-formaldehyde or phenol-formaldehyde. Mention may also be made of resorcinol-based adhesives such as tannin-resorcinol-formaldehyde or lignin-resorcinol-formaldehyde adhesives.

Mention may also be made of aminoplast, phenoplast or resorcinol glues without formaldehyde such as glues of urea-dimethoxyethanal, ethyleneurea-dimethoxyethanal, dihydroxyethyleneurea-dimethoxyethanal, melamine-dimethoxyethanal-polyols, the polyol of which is for example dipropylene glycol, polyvinyl alcohol, melamine-urea-dimethoxyethanal-polyols such as melamine-dimethoxyethanal-glycerol or melamine-dimethoxyethanal-dipropylene glycol-glycerol triethoxylate or melamine-dimethoxyethanal or finally phenol-dimethoxyethanal, resorcinol-dimethoxyethaninol and phenol. These aminoplast and phenoplast glues are sold by the company CLARIANT (France) in its Highlink® range.

Under preferential conditions for implementing the invention, an aminoplast adhesive with formaldehyde or a phenoplast adhesive is used.

In other preferential conditions for implementing the invention: in the case of aminoplast adhesives, these are based on a mixture of nitrogen / formaldehyde compound, preferably in the proportions of 1 / 0.2 to 3, in particular 1/1, 3 to 1, 6, especially 1/1, 5 approximately. in the case of phenoplast adhesives, these are based on a phenol / formaldehyde mixture, preferably in the proportions of 1 / 0.7 to 2.8, in particular 1 / 1.5 to 1.8, particularly 1 / 1.7 approximately.

The acetals can represent, for example, by weight from 1.7 to 25% of all the constituents of the adhesive, preferably from 1.7 to 20%, in particular from 3 to 18%, particularly from 5.5 to 15%. The resins and glues according to the present invention containing diacetals, particularly TME, have remarkable properties illustrated below in the experimental part.

The diacetals which they contain lower, for example, the viscosity and the surface energy of the resins and adhesives according to the present invention, which results in particular in a better capacity of impregnation of the substrates. Consequently, in particular, an improved resistance of the bondings produced is observed. Therefore, it is possible to significantly reduce the quantities of adhesive used to obtain the same bonding strength. Furthermore, the resins and adhesives according to the invention release little formaldehyde.

In addition, some acetals have a high boiling point and flash point.

For example, TME has a boiling point of 156 ° C and a flash point of 50 ° C, which in particular distinguishes it from lower monoacetals such as methylal, whose boiling point is 42.3 ° C and the flash point of -18 ° C. It is therefore considerably easier to use industrially and to transport.

Indeed, in addition to the fact that it is not toxic, it does not tend to evaporate strongly during its implementation. It should be remembered in this regard that in the context of uses as a binder for the manufacture of agglomerates, the kneaded wood chips are at a temperature of 30 to 50 ° C, often around 40 ° C, which causes losses significant volatile acetals by evaporation during manufacturing. In addition, the addition of a diacetal makes it possible to stabilize the resins and adhesives, in particular of the phenoplast type, particularly of the phenol-formaldehyde type. These properties justify the use of the resins and glues according to the invention in the manufacture of woody materials: agricultural waste and wood such as fiber boards, particle boards, oriented particle boards (Oriented Strand Boards or OSB), Medium and High Density Fiberboards (MDF), and other similar types of plywood.

This is why the present application also relates to agricultural waste and wood compositions such as fiber boards, particle boards, "Oriented Strand Boards" (OSB), "Medium and High Density Fiberboards" (MDF) , and other similar types of plywood panels containing the above resin or glue or prepared using the above resin or glue.

The present application also relates to a process for manufacturing agricultural waste and wood compositions such as fiberboard, particle board, "Oriented Strand Boards" (OSB), "Medium and High Density Fiberboards" (MDF ), and other types of similar and plywood panels, characterized in that it comprises the steps of mixing the substrate to be bonded with an above adhesive and of curing the finished product. These properties also justify the use of adhesives and resins according to the invention in the manufacture of impregnable substrates including laminated paper or cardboard and in particular decorative paper sheets or decorative laminates.

Indeed, conventionally, the manufacture of laminates using thermosetting resins is carried out by impregnating a paper support with various resins, for example phenolic or melamine-based, then drying and cutting. After drying and cutting, the coated papers (prepregs) are stacked and stored. The stratification phase allows, by stacking these sheets and hot pressing, to complete the reaction of the resins and thus to have the final product. There are also processes combining, after impregnation, drying and stratification.

This is why the present request also relates to laminated paper or paperboard containing a resin or glue above or prepared using a resin or glue above, as well as wood-based materials coated with such laminated paper or cardboard, by pressure-sensitive pressure pressing or by gluing with Using an adhesive, such as fiberboard, particleboard, Medium and High Density Fiberboards (MDF), and other similar types of plywood.

The present application relates as much to products prepared using such laminated paper or cardboard as worktops for kitchen, bathroom or laboratory, or floor coverings.

The resins and glues described above also have good sprayability and good water dilutability and thus find their application in the preparation of sizing compositions or binders for products based on mineral fibers, such as glass fibers, intended for thermal or acoustic insulation, or for sheets of glass fibers intended for reinforcement, for example roofing products or plastics.

The binders which generally contain other adjuvants such as silanes, mineral oils or nitrogen compounds can be applied according to traditional methods on the fibers, for example by spraying. Then, the fibers thus treated are usually subjected to a heat treatment to polycondense the resin and obtain a product having desired properties such as dimensional stability, tensile strength, resistance to humidity. This is why the present application also relates to a method for sizing the mineral fibers in which the fibers are glued by a conventional means such as spraying, using a resin or glue above.

Finally, in general, the invention relates to the use of a diacetal above in an adhesive or resin or for the preparation or the implementation of an adhesive or resin.

For this purpose, it is possible in particular to mix said glue or resin with elements to be bonded together, or deposit a layer of glue or resin between two surfaces to be bonded together. The present invention does not, however, relate to a surface coating.

The preferential conditions for using the resins and glues described above also apply to the other objects of the invention referred to above, in particular to agricultural waste and wood compositions and to laminated paper or board and their methods of preparation.

The following examples illustrate the present invention.

In the present application and in the following, the term "parts" means "parts by weight", "%" means "% by weight".

EXAMPLE 1 Preparation of an Aminoplast-type Glue

An aminoplast adhesive according to the invention was prepared as follows In a flask equipped with a condenser, a thermometer and a pH meter, 71 parts of formure are introduced (formaldehyde concentrate stabilized with urea, containing 54 % formaldehyde and 23% urea) to which 8.2 parts of urea and 19 parts of water are added. The pH is brought to a value between 10 and 10.4 by addition of a few drops of a 33% sodium hydroxide solution, and the temperature brought to 92 - 93 ° C with mechanical stirring. The pH decreases to a value of 7.8 and the reaction continues at the same temperature until the pH drops to a value of 5.2 in approximately 1 hour 30 minutes. A few drops of 33% sodium hydroxide solution are then added to the mixture, then 40 parts of melamine and 2 parts of dimethylformamide, while maintaining the temperature at 93 ° C. Water tolerance is tested every 10 minutes and the pH drops by itself. When the water tolerance is 180% - 200% (normally after 35 - 40 minutes and at a pH value of 7.2), 21, 4 parts of urea are added and the pH is brought to 9, 5. The reaction continues until reaching a water tolerance which must never be less than 150% (the pH has a value of 7.7 at this time). The pH is corrected to a value of 9.5 and the mixture is cooled and stored. A resin manufactured according to this procedure has a solid content of 58% to 65%, a density of 1,260 to 1,280 at 20 ° C, a viscosity of 70 to 150 mPa.s, a time of 55 to 60 s gel at 100 ° C with 3% hardener (ammonium sulfate).

To 100 parts of the above Melamine - Urea - Formaldehyde adhesive, 5 parts of TME and 3 parts of a 50% ammonium sulphate solution are added to obtain an adhesive according to the invention. The water tolerance test was carried out as follows:

1 g of resin in a test tube and added distilled water until the mixture turns white. Water tolerance TE was given by applying the formula

TE = (mass of water / mass of resin) x 100

EXAMPLE 2 Preparation of a glue of the phenoplast type

A phenoplast adhesive (phenol - formaldehyde) according to the invention was prepared as follows:

94 parts of phenol, 40 parts of a methanol / water solution (20/80) and 55 parts are placed in a flask equipped with a condenser, a thermometer, a pH meter and a mechanical stirrer. 96% paraformaldehyde. After 30 minutes of mechanical stirring at 40 ° C, the temperature is brought slowly to reflux (94 ° C). 20 parts of a 33% sodium hydroxide solution are added in 4 parts equal to 15 minutes apart. The mixture is left at reflux for 30 to 60 minutes and cooled in an ice bath. The color of the resin is pale yellow and its viscosity is between 180 and 750 mPa.s, corresponding to a solid content of 58 to 60%. 10 parts of TME and 5 parts of a 99% triacetin solution are added to 100 parts of the phenol-formaldehyde adhesive prepared above, to obtain an adhesive according to the invention.

Mechanical tests

1) Thermomechanical analysis (TMA)

Two boards of beech wood were assembled using the glue to be analyzed. Operating procedure

The principle of this method is based on a system for modeling the pressing of panels obtained by assembling two plates using the adhesive to be analyzed, the quality of the assembly obtained being directly linked to that of the sticky mixture used. More particularly, 30 mg of sticky mixture are deposited between two beech boards, and the assembly thus obtained is placed on a support so that said assembly is supported by its two ends, and the whole is placed in an oven. The oven is subjected to a temperature increase program from 25 to 250 ° C, at a rate of 10 ° C / min, which leads to a hardening of the adhesive between the two plates, and to the formation of a single solid wood plate. During the temperature rise, a force is applied vertically (F = 30 g) in the middle of the wafer, this force inducing a bending (f) which makes it possible to determine the modulus of elasticity. This flexion (f) decreases as a function of temperature, demonstrating an increase in mechanical strength. The apparatus used in this experiment is a "METTLER TMA 40" thermomechanical analyzer, connected to a processor and to a computer making it possible to record the thermograms and to process the data obtained. More specifically, and for each sample tested, the deflection (f in μm) was measured as a function of the temperature, and the elastic modulus (E in Mpa) was calculated according to the equation:

E = [1 / (f-3.2)] x 47386

Results

In Table I below are gathered the results obtained for the aminoplast adhesive of Example 1. BOARD

In Table II below are mentioned the results obtained for the phenolic glue of Example 2.

TABLE II

The results appearing in Tables I and II clearly demonstrate the effect of the TME on the modulus of elasticity measured and, consequently, on the increase in the mechanical resistance obtained.

2) Measurement of tensile strength on particle boards a) Preparation of the boards

To 1000 g of dry wood were added the amounts of the various constituents indicated in grams in Table III below.

TABLE III

The panels were pressed at a surface temperature of 190 ° C, at a maximum pressure of 28 Kg / cm ² , with a pressing cycle of 3 minutes, for a final panel thickness of 14 mm (pressing time 12, 8 sec / mm).

b) Results

On the panels thus obtained, tensile strength measurements were carried out, using the method described in European standard EN 319. The results obtained are listed in Table IV below.

TABLE IV

It first appears from these results that, all the other parameters being identical, the tensile strength obtained is clearly improved for the samples with TME compared to the controls (samples without TME). The addition of TME therefore makes it possible to reduce the amount of glue, while retaining comparable tensile strength. The present invention therefore makes it possible to obtain a reduction in the costs of the panels produced, and above all a reduction in formaldehyde emissions, both during the production and during the aging of the panels. In addition, since melamine is introduced into Urea - Formaldehyde adhesives to increase their mechanical resistance, the presence of TME therefore makes it possible to reduce the quantity of melamine necessary for equivalent mechanical resistance, which also contributes to a reduction in the price of adhesives and panels made from them. Finally, it should also be noted that the presence of TME in an aminoplast or phenoplast glue increases its compatibility with water. After its preparation, the degree of polymerization of an adhesive increases over time; the glue is then said to be more "advanced", which has the consequence of increasing the reaction speed of said glue during its use. However, the more a glue is polymerized, the lower its compatibility with water and therefore its ability to be diluted. The fact that the presence of TME in an adhesive increases its compatibility with water therefore has a double consequence, namely on the one hand for the same degree of polymerization, the compatibility with water is increased and, on the other hand , for the same compatibility with water, the degree of polymerization, and therefore the reaction rate during use, can also be increased.

EXAMPLE 3. Preparation of an aminoplast type adhesive without formaldehyde

An aminoplast adhesive without formaldehyde according to the invention was prepared as follows:

126 parts of melamine, 520 parts of a 60% aqueous solution of dimethoxyethanal (DME) and 164 parts of water are introduced into a reactor equipped with a condenser, a thermometer and a pH meter.

The pH is brought to a value of about 5.8 by addition of 20% sulfuric acid.

The reaction is maintained at 95 ° C for 3.5 hours with continuous stirring. 13

4.8 parts of urea are then added and the mixture is slowly cooled for 2 hours to room temperature.

Then added to 67 mg of aminoplast glue without formaldehyde above 5.1 mg of TME and 7.9 mg of SO (NH) ₂ in 20% aqueous solution to obtain a glue according to the invention.

EXAMPLE 4. Preparation of an aminoplast-type adhesive without formaldehyde

The procedure is as in Example 3, but replacing the TME with 1,1,3,3-tetramethoxypropane (TMP) (Acros catalog).

EXAMPLE 5. Preparation of an aminoplast-type adhesive without formaldehyde

The procedure is as in Example 3, but replacing the TME with 1, 1, 3,3-tetraethoxypropane (TEP) (Acros catalog).

Mechanical tests

Thermomechanical analysis (DMTA)

Two boards of beech wood were assembled using the different samples of glue to be analyzed in examples 3, 4 and 5 as well as with the witnesses below:

TABLE V

Operating procedure

40 mg of sticky mixture are deposited on each beech strip (38 x 8 x 0.5 mm) then a sandwich of beech strips is formed by 2004/0291

14

grouping of 2 plates, the assembly thus obtained is placed on a support and the whole is placed in an oven.

The oven is subjected to a temperature increase program from 40 to 250 ° C, at a rate of 4 ° C / minute. The applied force is 0.3 N, the frequency of 1 Hz and the strain (Strain) of 0.

The device used in this experiment is a DMTA Mklll, Rheometric Scientific in 3-point bending.

Results In Table VI below are collated the results obtained for the samples indicated.

TABLE VI

The results appearing in Table VI clearly demonstrate the effect of acetals on the modulus of elasticity measured, and therefore on the increase in mechanical strength obtained.

EXAMPLE 6 Preparation of a Phenoplast-type Glue A phenoplast glue (phenol-formaldehyde) according to the invention was prepared as follows:

400 g of 92% phenol and 22 g of 50% potassium hydroxide are incorporated in a reactor with magnetic stirring and heating in an oil bath. After bringing the mixture to 50 ° C., 282 g of 50% formaldehyde are added dropwise, then the mixture is heated to 85 ° C. in about 1 hour. At 85 ° C., the condensation stage is started. and the synthesis is stopped when the mass dilutability (water tolerance) is 40 g of water per 10 g of resin. Finally the mixture is cooled to 50 ° C in about 30 minutes and the pH is adjusted around 7 to 20 ° C by addition of HCl at 20%.

a) Viscosity evolution tests

Using a Brookfield LV ++ viscometer and drawing inspiration from standard NF T76-102, the influence of the addition of TME on the viscosity was measured. To do this, the mixtures were made just before use, under the following operating conditions:

- Mobile S00 Speed 5 rpm

- Temperature 20 ° C

Evolution of surface tension

The influence of the addition of TME on the surface tension was measured according to the method described in standard ISO 4311 using a Wilhelmy balance.

The mixtures are made just before use and taking the average of 3 readings for each% of TME.

Evolution of dilutability (water tolerance WT)

It is carried out by determining the quantity of water required to produce an irreversible turbidity even after 30 seconds of stirring of the water / resin mixture:

WT = added water mass / resin mass Evolution of paper penetration

The influence of the addition of TME on paper penetration was measured according to the method described in standard NF Q03-069. The apparatus consists of two containers connected by a flexible hose, one fixed, the other mobile, making it possible to ensure, when it is moved, a given water pressure in the test tube fixed to the first container: this water pressure forces the liquid to pass through the paper, but the time taken for the first drop to pass through the paper is variable and depends on the resistance of the paper to penetration.

A 180 g / m ² kraft paper is used and 2 values are noted for each test:

The time it takes to see a complete round area on the paper, representing the fact that the entire resin / paper contact surface has been impregnated,

The time required to have a drop actually formed on the surface.

Results

The results obtained are listed in Table VII below.

TABLE VII

These results show that:

The addition of TME lowers the viscosity, which is an interesting factor to facilitate the implementation of the adhesive, - The addition of TME rapidly decreases the surface tension of the PF resin and this very quickly after the addition of a few%, which will favorably influence the spreading of the glue on the support (paper for example) but also its ability to penetrate into the porosities and to be distributed therein in a homogeneous manner, - The addition of TME increases the dilutability , which indicates better compatibility between the PF resin and water as well as better stability, The results obtained on paper penetration are in agreement with the decrease in viscosity and surface tension, factors favoring impregnation .

Claims

1. An adhesive with high mechanical resistance, characterized in that it contains a diacetal, linear or cyclic, which can be prepared from C ₂ - CQ aldehydes and Ci - C- alcohols | ₂ .

2. An adhesive according to claim 1, characterized in that it contains a diacetal prepared from C ₂ - C ₄ aldehydes and Ci - Os- alcohols

3. An adhesive according to claim 1 or 2, characterized in that it contains a diacetal prepared from C ₂ - C ₃ aldehydes and Ci - C ₃ alcohols.

4. An adhesive according to one of claims 1 to 3, characterized in that it contains 1,1,2,2-tetramethoxyethane, 1, 1, 2,2-tetraethoxyethane, 1, 1, 2, 2, -tetrapropoxyethane, 1, 1,3,3-tetramethoxypropane or 1, 1, 3,3-tetraethoxypropane.

5. An adhesive according to one of claims 1 to 4, characterized in that it contains 1, 1,2,2-tetramethoxyethane.

6. An adhesive according to one of claims 1 to 5, characterized in that it contains any combination of two or three diacetals.

7. An adhesive according to one of claims 1 to 6, characterized in that it is an aminoplast adhesive, particularly of the melamine-urea-formaldehyde type.

8. Glue according to one of claims 1 to 6, characterized in that it is a phenolic glue, particularly of the phenol-formaldehyde type.

9. Glue according to one of claims 1 to 6, characterized in that it is an aminoplast, phenoplast or resorcinol adhesive, with or without formaldehyde.

10. Glue according to claim 7, characterized in that it is based on a mixture of nitrogen / formaldehyde in the proportions of

1 / 0.2 to 3.

11. Glue according to claim 8, characterized in that it is based on a phenol / formaldehyde mixture in the proportion of 1 / 0.7 to 2.8.

12. Glue according to one of claims 1 to 11, characterized in that the acetal or acetals represent by weight from 1, 7 to 25% of all the constituents of the glue.

13. Agricultural waste or a composition of wood such as fiberboard, particleboard, Oriented Strand Boards (OSB), Medium and High Density Fiberboards or MDF), and other similar types of plywood panels containing an adhesive as defined in one of claims 1 to 19 or prepared using such an adhesive.

14. A laminated paper or cardboard containing a resin or glue as defined in one of claims 1 to 12 or prepared using a resin or glue above, or a product prepared using such laminated paper or cardboards .

15. A method for sizing fibers in which fibers are seamed using a resin or glue as defined in one of claims 1 to 12.